add scale sentence

Author: vladvelici

src/pages/docs/guides/chat/build-embedded-chat.mdx

@@ -33,6 +33,8 @@ Despite the challenges of delivering these guarantees, Ably is designed to keep
 
 The most important decision when developing embedded chat applications is the experience you want users to have within their specific context. This will determine how chat integrates with your task flow and ultimately how effectively it enhances the user experience.
 
+Ably has been tested to handle millions of concurrent connections and rooms. Whether you're managing 100 support conversations or 100,000 simultaneous delivery chats, the architecture remains the same - no re-engineering required as you grow.
+
 For large-scale chat scenarios with many users per room, see our [building livestream chat guide](/docs/guides/chat/build-livestream).
 
 **Room architecture:** The optimal approach for contextual chats is one chat room per context or task, where all participants join to communicate within that specific context. Rooms are: